Identification of genetic modifiers of tdp‐43: Inflammatory activation of astrocytes for neuroinflammation

Transactive response DNA‐binding protein 43 (TDP‐43) is a ubiquitously expressed DNA/RNA‐binding protein linked to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). TDP‐43 has been implicated in numerous aspects of the mRNA life cycle, as well as in cell toxicity and neuroinflammation. In this study, we used the toxicity of the TDP‐43 expression in Saccharomyces cerevisiae as an assay to identify TDP‐43 genetic interactions. Specifically, we transformed human TDP‐43 cDNAs of wild‐type or disease‐associated mutants (M337V and Q331K) en masse into 4,653 homozygous diploid yeast deletion mutants and then used next‐generation sequencing readouts of growth to identify yeast toxicity modifiers. Genetic interaction analysis provided a global view of TDP‐43 pathways, some of which are known to be involved in cellular metabolic processes. Selected putative loci with the potential of genetic interactions with TDP‐43 were assessed for associations with neurotoxicity and inflammatory activation of astrocytes. The pharmacological inhibition of succinate dehydrogenase flavoprotein subunit A (SDHA) and voltage-dependent anion‐selective channel 3 (VDAC3) suppressed TDP‐43‐induced expression of proinflammatory cytokines in astrocytes, indicating the critical roles played by SDHA and VDAC3 in TDP‐43 pathways during inflammatory activation of astrocytes and neuroinflammation. Thus, the findings of our TDP‐43 genetic interaction screen provide a global landscape of TDP‐43 pathways and may help improve our understanding of the roles of glia and neuroinflammation in ALS and FTD pathogenesis.